1. Field of the Invention
The invention relates to a device for intelligently directing light to a particular object in a scene and then directing the light reflected from the object into an imaging camera.
2. Background of the Invention
There are several methods known as biometrics used for verifying or recognizing the identity an individual. Verification is a one-to-one process in which a computed biometric code from an individual is compared to a single previously stored biometric code to determine if the person is who he or she claims to be. Recognition is a one-to-many process in which a computed biometric code from an individual is compared to a data base of many different individuals' biometric codes with the objective of determining the identity of the individual. Biometric methods include analyzing a signature, obtaining and analyzing an image of a fingerprint and imaging and analyzing the retinal vascular patterns of a human eye. Recently, the art has used the iris of the eye which contains a highly detailed pattern that is unique for each individual and stable over many years as a non-contact, non-obtrusive biometric. This technique is described in U.S. Pat. No. 4,641,349 to Flom et al. and U.S. Pat. No. 5,291,560 to Daugman.
The iris identification techniques disclosed by Flom and Daugman require a clear, well-focused image of the iris portion of the eye including a well defined iris sclera boundary. Additionally, the image must be of sufficient size so that it may be encoded properly. The nominal size of the iris must be approximately 200 pixels in diameter for a 640 by 480 by 8 bit digitized image.
In a present commercial embodiment, the IriScan System 2100, manufactured by IriScan of Marlton N.J., an image of the eye is obtained and an iris code is derived from the image. This code is stored along with other data in a file for a particular individual thereby completing an enrollment process. Later, when that same person asks to be verified, a new image of the eye is obtained and used to compute an iris code which is then compared with the iris code on file. In this way, a person's identity can be verified. In order to obtain an enrollment or a verification image the person being identified must keep at least one of their eyes in a fixed position with respect to a single imaging camera which takes a picture of the iris. To accomplish this, the user must look at a either a reflected or real time video image of their eye (i.e. a visual feedback mechanism) and then move their face slightly back and forth or left and right until an aligned, well focused, and complete image is obtained. Since focus is a subjective measurement, image processing software is used to make the final judgment of the focus and positioning of the eye and notifies the user by an audible signal when the user's eye is properly aligned. While this procedure is satisfactory for some applications, it is not satisfactory for quick transactional activities such as using an automated teller machine, automated cash dispensing machine or certain access control applications since it requires cooperation from the user.
However, prior to the present invention or U.S. Pat. No. 5,717,512 to Chmielewski et al, there has not been an optical system which could rapidly acquire a sufficiently clear, properly aligned image of an iris of the person to be identified unless that person positioned his eye in a fixed position relatively close to an imaging camera and performed a self alignment and focus process. Thus, there is a need for an optical system which will rapidly obtain a clear, properly aligned picture of the iris of a person standing remotely from the optical system and in an uncertain position. This system should be as unobtrusive as possible. That is, it should require little or no cooperation by the user (except for looking in the right direction) and not do anything out of the ordinary such as turning on or off bright lights. This type of system would be particularly useful to verify or recognize the users of automated teller machines as well as individuals seeking access to a restricted area or facility or other applications requiring user identification.
Automated teller machines, often called ATMs, are compact, sophisticated devices which have a large number of electrical and electromechanical subsystems arranged in a restricted volume. Cash machines are simpler derivatives of ATMs that only dispense cash. The terms automated teller machine and ATM are used herein to include cash machines. There are small spaces immediately behind the cover plates of these automated machines or around the bezel of the display in which a very compact optical system could be placed. The location and size of that space may differ among automated teller machines. Alternatively, the top surface of the ATMs also provides a convenient location for mounting an optical system. Yet, there are several manufacturers of these machines, two of which are NCR and OKI Electric. Each manufacturer offers several models, but the products in each manufacturer's ATM product line are quite similar. Although there are several basic types of ATMs, the NCR machine and the OKI machine are representative. Any optical system for iris identification of ATM users should be suitable for use either integrated into the ATM or attached to the top of the ATM. In this way the system can accommodate the various types of ATM machines. The system must also be able to rapidly capture a clear image of the iris of the person using the automated teller machine and have the capability of performing the related processing needed for user verification or recognition.
Many automated teller machines and similar financial transaction machines are currently equipped with video cameras typically positioned above the display panel. These video cameras are used to record images of people making transactions and also for general security such as to catch vandals. These cameras are positioned to take a picture of the head and shoulders of the person using the machine. However, these cameras are not equipped to rapidly focus on or image a small region of the user's face. It is not possible for these cameras to obtain a sufficiently detailed image of the iris of the user of the machine which iris image could be used to verify or recognize the user. Therefore, there is a need for an optical system compatible with the ATM within the size constraints and normal use of the machine which can rapidly acquire and provide a clear, detailed image of the iris of the user which image is sufficient for identification of the user based upon iris analysis. Preferably, at least one of the cameras used within this optical system could also serve as a conventional security camera when the device is not in use thereby reducing cost by removing duplicated equipment.
In our U.S. Pat. No. 5,717,512 we describe a compact image steering and focusing device having three cameras and a tilting frame on a flat base. The tilting frame contains a pan/tilt mirror, lens system, focus motor, pan motor, and tilt motor, all of which can direct the field of view seen by one of the cameras. The other two cameras are mounted in fixed locations. The illuminators are also fixed and provide illumination sufficient to image an iris anywhere in the defined working volume. Although this device works well, it has limitations which prevent it from covering a larger imaging volume (i.e., one that is sufficient to image users ranging from the average 7 year old to the 95th percentile male as well as wheelchair bound individuals) in a cost effective manner. Therefore there is a need for a cost effective system that can unobtrusively image the iris of individuals, adaptively compensating for a wide variety of eye heights and also be compact enough to be integrated either into or on top of an ATM or cash machine.